Turf grasses are utilized for functional, recreational and aesthetic purposes, including, but not limited to, the playing surfaces of turf facilities of golf courses, parks, sports fields, cemeteries, highway right-of-ways and industrial and home lawns. Intensive use of a turf area and maintenance operations often result in turf wear and soil compaction. This compaction reduces large, or macro, pore space and total pore space in the soil which in turn reduces water infiltration into the soil, percolation through the soil, and drainage out of the soil; limits exchange of soil gasses, especially soil oxygen, with the atmosphere; and tends to restrict and reduce root growth and development of turf grasses, for example, causing, in some cases, substantial reduction of the root system and often death of deeper roots.
The proper cultivation of turf to enhance drainage, and thereby thorough root growth, and improve the soil-air-water relationship has long been a problem within the industry and a great number of devices have been proposed in the past in an effort to find a solution.
Core cultivation (aerification) is widely utilized as a long term program to alleviate compacted conditions in the soil root zone. Several different types of core cultivation equipment are available commercially. One such type is The Toro Company's Greens Aerator. Core cultivation equipment utilizes vertically operating hollow or solid metal tines which are forcibly driven into the turf to a depth of 21/2 to 3 inches and extract a plug, or core, of the turf which is then deposited on the turf surface of the green. In all instances, the cores are collected and removed from the green and may be dried and used in a mix which is returned to the green to fill the holes. Research has shown that core cultivation creates a serious problem. Repeatedly forcing the metal tines into the turf to a common depth will, over time, create a compacted subsurface layer of soil, sometimes called "plow sole," at a depth about 1 inch deeper than the length of the tines, in other words at about 31/2 to 4 inches below the surface of the turf. Further, the metal tines also tend to glaze the soil and create some compaction along the sides of the coring hole. This subsurface compaction creates two major problems with turf management. First, the compacted layer interferes with proper water movement within the soil, and second, the compacted soil interferes with proper root growth of the turf grasses. In addition to the compaction problem, core cultivation creates another problem--the removal or utilization of the removed turf cores. Present techniques often leave a golf green unplayable for two to three days after treatment. The high pressure liquid containment joint of the present invention is incorporated in an apparatus which will allow immediate turf and subsoil treatment at the time treatment is needed rather than waiting for a convenient time, and thus allows immediate use of the treated turf.
The high pressure liquid containment joint of the present invention is incorporated in a unique apparatus for accomplishing subsoil cultivation which utilizes periodic turf and soil injection of a substantially incompressible liquid, such as water, in a pattern, and at sufficient pressure, to lift and fracture the soil to reduce the compaction, or general density, of the treated area. The apparatus, in utilizing high pressure liquid to cultivate turf, incorporates components for pressurizing and routing the high pressure liquid. The components include a high pressure pump, a pump head incorporating various water passages and check valves, an accumulator for storing pressurized water and a discharge manifold with nozzles. These components incorporate high pressure liquid seals at various joints to contain the high pressure liquid. These high pressure liquid containment joints must have a high degree of structural integrity in an environment with high liquid pressure loads and high frequency pressure spikes while, at the same time, forming a liquid impermeable barrier. Such joints typically incorporate fastening means, such as threads, on the components to be joined, and a resilient sealing member, such as a flexible O-ring, which forms a liquid impermeable barrier when the threaded joint is tightened.
Prior art high pressure liquid containment joints incorporate various combinations of O-rings and threads to form liquid impermeable barriers while maintaining some degree of structural integrity. One prior art high pressure liquid containment joint, e.g., as shown in SAE Standard J514 dated 1980, incorporates an O-ring, a cylindrical plug with external threads located between the two ends of the plug, and an internally threaded containment vessel for accepting the cylindrical plug. When the threaded plug is engaged with the internal threads on the containment vessel and the plug is rotated, the plug is drawn into the containment vessel wherein one end of the plug contacts the high pressure liquid. The O-ring is located between the external threads of the plug and the plug end opposite the high pressure liquid. Accordingly, the high pressure liquid surrounds, contacts and exerts considerable force on the threaded portion of the joint since the high pressure liquid is restrained only by the O-ring, which does not protect the threads from the high pressure liquid. This particular prior art joint incorporates a smooth, tapered seat located just above the internal threads of the containment vessel. The seat is tapered so that the resilient O-ring, which is placed on the plug before the plug is tightened into the internally threaded containment vessel, will slide down and will seat on the smooth tapered surface without crushing or otherwise damaging the O-ring as the plug is tightened. While this particular high pressure liquid containment joint is effective in creating a liquid impermeable barrier, it does subject the threaded portion of the joint to substantially high stresses since the high pressure liquid contacts and surrounds the threads. The threaded portions of the joint, especially the internally threaded area of the containment vessel, are inherently more susceptible to stress induced failures due to the stress concentration factors associated with threads.
Another prior art high pressure liquid containment joint, e.g., as shown in U.S. Pat. No. 4,817,994, incorporates a resilient O-ring, a cylindrical plug with external threads located between the two ends of the plug, and an internally threaded containment vessel for accepting the cylindrical plug when the externally threaded plug is engaged with the internal threads on the containment vessel. When the threaded portion of the containment vessel, which rotates freely relative to the remainder of the containment vessel, is rotated, the plug is drawn into the containment vessel. In this prior art high pressure liquid containment joint design, the O-ring is located on the flat end face of the plug that contacts a flat sealing surface on the liquid containment vessel. Since the threaded portion of the containment vessel rotates and draws the plug into the remainder of the containment vessel, the plug and the remainder of the containment vessel do not rotate relative to each other. Since the flat end face of the cylindrical plug and the flat sealing surface of the liquid containment vessel do not rotate relative to each other, the O-ring, which nests in a circumferential ring groove on the plug face and which also does not rotate relative to these two surfaces, is not damaged as the plug is drawn into the containment vessel. As the plug is drawn into the vessel, the O-ring contacts the sealing face and a liquid impermeable barrier is formed. Accordingly, the threaded portions of this high pressure liquid containment joint are not exposed to high pressure liquid. The threaded portions of this joint are, therefore, not directly subjected to the high pressure liquid loads, resulting in reduced stress on the threaded portions of the joint. However, as noted above, this joint does require the use of a high pressure containment vessel that incorporates a threaded portion which rotates independently of the remainder of the containment joint.
Another prior art high pressure liquid containment joint, e.g., as shown in Fluid Line Products, Inc.'s Uniport 10K System brochure, incorporates a resilient O-ring, an inner cylindrical plug with two ends, an outer cylinder concentrically surrounding the inner plug wherein the outer cylinder incorporates external threads located between the two ends of the outer cylinder, and wherein the liquid containment joint includes an internally threaded liquid containment vessel for accepting the inner plug and outer cylinder when the externally threaded cylinder is engaged with the internal threads of the containment vessel. The outer cylinder engages the inner plug so as to transfer the axial movement of the outer cylinder to the inner plug without transferring the rotational movement of the outer cylinder to the inner plug. The engagement of the outer cylinder to the inner plug is accomplished by a heat treated pressure ring which seats in an internal groove on the outer cylinder and an external groove on the internal plug, allowing the transmission of axial force between the cylinder and plug but prohibiting rotational force transmission between the two members. The resilient O-ring mounts on the inner plug in a circumferential groove located near the end of the inner plug which extends beyond the outer cylinder. When the outer cylinder, which retains the inner plug, engages the internal threads of the containment vessel and is rotated, the outer cylinder and the inner plug move axially into the containment vessel. The resilient O-ring, which is mounted on the internal plug, engages a smooth, cylindrical seat on the containment vessel as the outer cylinder is rotated and tightened in relation to the containment vessel. Since the O-ring moves only axially but does not rotate since it is mounted on the inner plug, the O-ring seats against the smooth, cylindrical seat in the containment vessel without incurring any substantial damage that would be incurred if the O-ring moved axially and rotationally along the cylindrical seat. The O-ring and the smooth, cylindrical seat seal the high pressure liquid in the containment vessel from the internal threads of the containment vessel and the external threads of the outer cylinder. The threaded portions of this high pressure joint, therefore, are not directly subjected to the high pressure liquid loads, resulting in reduced stress on the threaded portions of the joint. However, as noted above, this joint does require a separate outer cylinder which transmits axial, but not rotational, motion to the plug. This additional component permits the resilient O-ring to seal against the smooth cylindrical surface without subjecting the O-ring to any substantial damage.
The present invention addresses the problems associated with the prior art high pressure liquid containment joints discussed above. In particular, a preferred high pressure liquid containment joint according to the present invention incorporates the fewest possible number of parts while providing a liquid impermeable seal that protects the threads from being contacted by the high pressure liquid which, in turn, results in lower stresses on the threaded portions of the joint. A preferred high pressure liquid containment joint according to the present invention incorporates a plug with a first end and a second end and a liquid sealing element and external threads between the ends of the plug and means for accepting the liquid sealing element between the external threads and the second end and means on the plug for accepting rotational force. A preferred embodiment of the high pressure liquid containment joint of the present invention also incorporates a high pressure liquid containment vessel in fluid communication with a liquid pressurizing means wherein the vessel includes means for accepting the plug, the means including internal threads for engaging the external threads of the plug and means for contacting the liquid sealing element wherein the liquid sealing element and the contacting means form a liquid impermeable barrier when the external threads engage the internal threads and wherein the plug and said O-ring rotate relative to the containment vessel and wherein the barrier lies between the high pressure liquid and the external and internal threads whereby stresses on the internal threads of the containment vessel are reduced resulting in a reduced chance of failure of the containment vessel.